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411.
新疆北天山中东段地区震源参数研究 总被引:9,自引:2,他引:9
本文首先利用经验格林函数方法证明了新疆北天山中东段地区的震源谱基本满足ω-2 模型。在此基础上 ,通过对S波观测谱中的噪音、仪器、路径、场地等影响的逐一消除 ,得到了研究区 10 5次ML2 5~ 5 7地震的震源谱 ,进而根据Brune的圆盘震源模型计算了地震矩、应力降、震源半径等震源参数。结果表明 ,这些地震的标量地震矩M0 与ML 震级线性相关较好 ,关系为Log10 M0 =1 10ML+ 17 2 0 ;震源半径在 10 0~ 15 0 0m之间 ;应力降介于 1~ 16 0bar之间 ,优势分布于 1~ 10 0bar。地震矩与拐角频率的关系呈现出两段趋势 ,可能表明了研究区震源的多重标度特征 :当M0 小于 4× 10 2 1dyne cm时 (相当于ML4 0地震 ) ,应力降显示出对M0 有依赖关系 ;当M0 大于 4× 10 2 1dyne cm时 ,地震的应力降不依赖于M0 。 相似文献
412.
建立能够反映储层孔隙结构、流体特征的逾 渗网络模型,通过数值模拟研究了储层孔隙尺寸、 孔隙形状、连通性、微孔隙的发育状况等对I-Sw曲 线影响的定性规律,研究了地层水矿化度对岩石电 阻率的影响。分析讨论了不同因素对电阻率影响的 相对强度。最后,通过曲线拟合定量地研究了不同 因素对I-Sw曲线的影响规律。研究表明,在上述影 响因素中连通性和微孔隙对I-Sw曲线的影响很大, 其它因素的影响强度较小。地层水矿化度对岩石电 阻率绝对值的影响很大。“非阿尔奇”现象普遍存在, 在低渗透(低连通性)储层岩石中更为明显。 相似文献
413.
Introduction The Great North China, located at longitude 106E to 124E and latitude 31N to 42N, in-cludes three secondary active tectonic blocks, Ordos, Yanshan and North China plain (Figure 1). The geological tectonics of these three secondary blocks is much different from each other. As a stable block with high rigidity, the Ordos block is mostly surrounded by down-faulted basins with an inactive interior since Cenozoic, although the fault zones along its boundary are strongly active wi… 相似文献
414.
Distribution of chlorophyll-a off the Changjiang River and its dynamic cause interpretation 总被引:1,自引:1,他引:1
ZHU Jianrong State Key Laboratory of Estuarine Coastal Research East China Normal University Shanghai China 《中国科学D辑(英文版)》2005,48(7)
Red tide,also called harmful algal bloom interna-tionally,is a disaster abnormal phenomenon of oceanecology with an explosive breed or dense assemble ofone or several phytoplanktons in a specific ocean en-vironment condition,colors the seawater,influencesand harms ocean living things.The formation of redtide is controlled mainly by a complex interplay ofbiological,physical and chemical processes,but themost main cause influencing the occurrence of red tideis the seawater eutrophication,i.e.,the… 相似文献
415.
The model for the 2000 dike intrusion event between Kozushima and Miyakejima volcano, Japan, was reinvestigated. After the sudden earthquake swarm in Miyakejima volcano, a dike intrusion of large volume was detected by the nationwide GPS network (Geonet). The displacements detected with GPS stations over an area with a radius of about 200 km shows a distribution that is consistent with the dike source being located near Miyakejima volcano.The dike was intruded northwestwards between Miyakejima and the neighboring Kozushima volcano. We searched for the parameters in the models that reproduce the regional displacements due to dike intrusion between Miyakejima and Kozushiima islands. We tested three models, (1) the model with a single dike, (2) the model with a dike and a point dislocation source which represents a creep dislocation source and (3) the model with a dike and a deflation source which represents a magma reservoir. Though all three models can match the horizontal displacements near the source area, model 1 fails to reproduce the regional displacements in the central part of Japan. Both models 2 and 3 can reproduce the regional displacement for horizontal components. Model 3 produces slightly better results than model 2 for vertical components. The balance in the volume budget for models 2 and 3 is also consistent with the observations. These results show that we cannot distinguish between the two models using only GPS observation. As there is no direct evidence for such a large creep or ductile source (corresponds to M7 or more) as proposed in model 2 and the active seismic region migrated back and forth within the linear swarm region, the model with a dike and a deep magma source is preferable. For the deflation point source, we obtained a deflation volume of 1.5 km3 at the depth of 20 km below the dike. An additional ~0.95 km3 of volume loss through caldera collapse and edifice deflation took place at Miyakejima. We conclude that the magma that intruded the dike came in part from below Miyakejima and in part from below the sea floor between Miyakejima and Kozushima, perhaps from reservoirs at the Moho.Editorial responsibility: S Nakada, T Druitt 相似文献
416.
The chemical forms, spatial distribution and sources of As, Hg, Cd, Pb and Zn in sediments of the Miyun reservoir were studied. The results of sequential extraction demonstrate that most of As, Pb and Zn were bound to the residual fraction, Hg was associated with the sulfide fraction while Cd was associated with the carbonate fraction and the residual fraction. On the vertical profiles the concentrations of the heavy metals in total and each fractions mostly decreased with increasing depths in sediments, suggesting that the heavy metals input from the upstream watershed increases yearly. Summation of the residual fraction, the sulfide fraction and the carbonate fraction accounts for 60.03%―85.60% of the total heavy metal contents in the sediments, which represent the geochemical background values of the elements and relate closely to soil erosion. Results of the main factor analysis show that most sediments of the reservoir come from the upstream soil erosion, the point source pollution and domestic waste. Moreover, the microbial activities taking place on the sediment-water interface are also one of the major factors to cause the increasing content of the organic matter fraction and the iron-manganese oxide fraction. Environmental change of the reservoir water could make the removability of the heavy metals increase, leading to the increase of their concentrations in pore water in sediments, and imperiling water quality of the reservoir. 相似文献
417.
Huang Qingtuan 《中国地震研究》2005,19(2):214-223
INTRODUCTION TheLonghai ZhangpucoastalareaofFujianProvinceliesonthesouthernsideoftheoutletofthe JiulongjiangRiver.Tectonically,itislocatedonthesouthernsegmentoftheChangle Zhao’anfault zone.Previously,alotofseismogeologicresearchworkhasbeencarriedoutinthi… 相似文献
418.
Zhou Bengang 《中国地震研究》2005,19(4):430-441
INTRODUCTIONThe method of probabilistic seismic risk analysis was proposed by Cornell in1968(Cornell,1968).After more than30years development,it has become the main method for seismic riskassessment of engineering sites and seismic zonation,and has been u… 相似文献
419.
研究区虎睛石矿床在地质特征、矿物组合、化学成分及琢雕效果等方面与国外虎睛石矿床是完全不同的,属于一种特殊的罕见类型。在分析虎睛石地质特征、开发利用现状的基础上,认为该区的虎睛石资源丰富,琢雕效果好,在国内外市场上具有一定的竞争力和良好的开发利用前景。 相似文献
420.
致密砂岩的形成机制及其地质意义——以塔里木盆地英南2井为例 总被引:7,自引:0,他引:7
砂质岩的孔隙和喉道被网格状粘土矿物和次生加大矿物充填成微细孔喉状结构时,形成具有较高毛细管压力的致密砂岩。它与地层水发生水锁效应,可大大降低渗透率,成为致密砂岩盖层。当含水饱和度在50%以下时,束缚水饱和度比较低,致密砂岩储层可以产气;当含水饱和度在50%~90%区间时,具有较高的束缚水饱和度,相对渗透率非常低,它既不能产气也不能产水,反映为渗透率瓶颈区(具有盖层性质);当含水饱和度大于90%以上时,致密砂岩储层仅微量产水。塔里木盆地英南2井侏罗系气藏盖层由致密砂岩构成,不含水时的气体渗透率在(0.027~0.081)×10-3μm2,不能构成封堵;当含水饱和度达到60%以上时,相对渗透率几乎为零,构成有效盖层。 相似文献